Heater

Abstract

A heater assembly 1, 20 includes a heating element 4, 21 comprising a ceramic substrate 5, 22 and a heat sink element 2, 30 disposed on a surface of the ceramic substrate. The heat sink element includes at least one heat dissipation member 6, 32 comprising a base 7, 34 having an underside that faces a surface of the ceramic substrate, a tab 9, 40 extending from the underside of the base towards the surface of the ceramic substrate and a heat dissipation fin 8, 36, 38 extending from the base in a direction away from the surface of the ceramic substrate. The heater assembly further includes a braze filler material 3, 24 bonding the heat sink element to the surface of the ceramic substrate, the braze filler material located between the underside of the base portion and the surface of the ceramic substrate and around the tab portion.

Description

B ACKGROUND A heater assembly may be used to heat airflow through a haircare appliance. The heater assembly may comprise a heat sink that dissipates heat into the airflow. SUMMARY According to a first aspect, there is provided a heater assembly comprising: a heating element comprising a ceramic substrate; and a heat sink element disposed on a surface of the ceramic substrate, the heat sink element comprising: at least one heat dissipation member, wherein the heat dissipation member comprises: a base comprising a base portion having an underside that faces the surface of the ceramic substrate; a tab portion extending from the underside of the base portion towards the surface of the ceramic substrate; and a heat dissipation fin extending from the base in a direction away from the surface of the ceramic substrate, the heat dissipation fin for dissipating heat produced by the heating element, wherein the heater assembly further comprises: a braze filler material bonding the heat sink element to the surface of the ceramic substrate, the braze filler material located between the underside of the base portion and the surface of the ceramic substrate and around the tab portion. The tab portion may provide better contact between the heat dissipation member and the ceramic substrate compared to a heat dissipation member that does not include the tab portion, especially when the surface of the ceramic substrate to which the heat dissipation member is attached is not flat. This may reduce the need to provide a flat surface on the ceramic substrate, which may reduce the cost and time taken to manufacture the heater assembly. When a flat surface is required, additional manufacturing steps may be needed in order to create a smooth surface on the ceramic substrate. These additional manufacturing steps may be omitted due to the presence of the tab. When the tab portion is not present, the base (and / or the material forming the base) may also need to have a thickness within a tight tolerance to ensure good connection between the base and the ceramic substrate. Providing the tabs in the base may reduce the need for such tight tolerances, which may reduce the manufacturing costs associated with the heater assembly. The tab portion may also provide a wicking path to encourage the braze filler material to travel from the ceramic substrate toward the base. This may improve thermal contact between the ceramic substrate and the heat dissipation member by ensuring that the braze filler material fills a gap between the heat dissipation member and the ceramic substrate. The tab portion may also allow the base to be positioned further away from the ceramic substrate compared to when the tab portion isn’t present. The braze filler material may fill a gap between the base and the ceramic substrate and the braze filler material may help to absorb thermal strain between the ceramic substrate and the base, caused by the ceramic substrate and the base having different coefficients of thermal expansion. Brazing may provide a strong joint between the fin and the ceramic substrate without the need to melt one or both of the heat dissipation member and the ceramic substrate. As such, this may reduce the likelihood of damaging one or both of the heat dissipation member and the ceramic substrate when bonding the heat dissipation member to the ceramic substrate. The base being position further away from the ceramic substrate may also allow a fixture used to apply a force to the base during brazing to be located further away from the site of the brazing. This may reduce the risk of an interaction occurring between the braze filler material and the fixture which may otherwise reduce the expected usable life of the fixture. This may also allow cheaper fixtures (for example, fixtures made of stainless steel) to be used which may reduce costs associated with forming the heater assembly. The tab portion may be integrally formed with the base. By integrally forming the tab portion with the base, no additional material needs to be added to the base to form the tab portion. This may speed up the manufacturing of the heat dissipation member and may also reduce costs associated with forming the tab portion. Moreover, as the tab portion is integrally formed with the base, there may not be a need for any mechanical connection between the base and the heat dissipation member, which may reduce the likelihood of such a connection failing. This may help to improve the lifetime of the heat dissipation member and therefore also of the heater assembly. The heat dissipation fin may be integrally formed with the base. The tab portion may be formed by a discontinuity in the base. The discontinuity may create a gap in the base into which the braze filler material may wick (e.g. via capillary action). This may improve a thermal connection between the ceramic substrate and the heat dissipation member. The tab portion may be formed by stamping the base, which may involve breaking the surface of the base, for example using a sharp tool, to push out the tab portion from the base. When the tab portion is formed in this way, no material needs to be added or removed from the base to form the tab portion. This may speed up manufacture of the heat dissipation member and may help to minimise waste. The tab portion may be deformable such that the tab portion may comply with the surface of the ceramic substrate to which it is bonded. The tab portion may be deformable relative to the ceramic substrate. This may help to bond the base to the surface of a ceramic substrate that is uneven. The tab portion may comprise a substantially triangular or trapezium shape. The tab portion may comprise a substantially quadrilateral shape, such as a rectangular shape The tab portion may have a length of no greater than 1.4 mm and / or a height relative to the underside of the base portion of no greater than 1.0 mm, and optionally the tab portion may have a length of between 0.5 mm and 1.0 mm and / or a height relative to the underside of the base portion of between 0.4 mm and 0.8 mm. The tab portion may have a height relative to the underside of the base portion of between 0.5 mm and 0.7 mm, such as 0.6mm. An angle formed between the tab portion and the underside of the base portion may be oblique. An oblique angle between the tab portion and the underside of the base portion may allow the tab portion to deform towards the underside of the base portion more easily than if the tab portion was orthogonal to the underside of the base portion. This may help the tab portion comply with an uneven surface of the ceramic substrate. The base may be substantially parallel to the ceramic substrate. The base may extend in a first plane and the heat dissipation fin may extend in a second plane that is orthogonal to the first plane. The tab portion may extend in a third plane different from the first plane and the second plane. The tab portion may be located on a first side of the first plane and the heat dissipation fin may be located on a second, opposite side for the first plane. The base may have a first edge proximal to the heat dissipation fin and a second edge distal from the heat dissipation fin, and the tab portion may extend from the underside of the base portion at a location between the first edge and the second edge. The base may comprise a plurality of spaced apart base portions, each of the plurality of base portions having an underside that faces the surface of the ceramic substrate; and the at least one heat dissipation member may comprise a plurality of tab portions, a respective one of the plurality of tab portions extending from the underside of each of the base portions towards the surface of the ceramic substrate, wherein, the heat dissipation fin extends in a direction away from the plurality of base portions and the braze filler material is located between the underside of each of the plurality of base portions and the surface of the ceramic substrate and around each of the tab portions. The spaced apart base portions mean that the base is not bonded to the ceramic substrate along its entire length such that there are gaps or breaks in the bond. These gaps may enable stress between the heat dissipation member and the ceramic substrate to be relieved. When the ceramic substrate is at high temperature or transitioning to or from ambient temperature, the heat dissipation member may expand or contract more than the ceramic substrate. The gaps or breaks may enable the heat dissipation member to expand and deform without causing excessive stress to the ceramic substrate. The use of a plurality of tab portions may increase the strength of joint between the heat dissipation member and the ceramic substrate compared to if only a single tab portion was used, as there are more points of connection between the heat dissipation member and the ceramic substrate. The plurality of tab portions may also provide improved thermal connection between the ceramic substrate and the base as more wicking paths are provided. The plurality of tab portions may also provide better compliance between the ceramic substrate and the heat dissipation member. Each tab portion of the plurality of tab portions may extend from the underside of a respective base portion of the plurality of base portions in substantially the same direction. The tab portions of the plurality of tab portions all extending in the same direction may be easier to manufacture than if the tab portions extend in different directions. The tab portions may extend from the base portions in different directions. The tab portions may extend from the base portions in alternating first and second directions. The heat dissipation member may comprise a metallic material, such as copper or aluminium. The metallic material may allow the heat dissipation member to easily conduct heat from the ceramic substrate and dissipate the heat into a surrounding environment. The heat dissipation member may comprise a first heat dissipation fin and a second heat dissipation fin, the first heat dissipation fin is coupled to a first edge of the base, and the second heat dissipation fin is coupled to a second, opposite edge of the base. The use of the first heat dissipation fin and the second heat dissipation fin may increase the amount of thermal mass available to conduct heat away from the heating element. The first heat dissipation fin and the second heat dissipation fin may be spaced apart by less that 2mm, such as less than 1.75mm or less than 1.5mm. The heat sink element may comprise a plurality of heat dissipation members. By increasing the number of heat dissipation members in the heat sink element, this may increase the thermal mass of the heat sink element, which may increase the amount of heat that can be dissipated. A height of the plurality of heat dissipation members may vary over a width of the heat sink element. This may allow the heat sink element to be more compact and therefore take up less room. The plurality of heat dissipation members may have a maximum height near a centre point of the heat sink element and a minimum height near the edge of the heat sink element. Directly adjacent heat dissipation members may be spaced apart by less that 2mm, such as less than 1.75mm or less than 1.5mm. The plurality of heat dissipation members may be integrally formed. This may allow the plurality of heat dissipation members to be assembled before being bonded to the ceramic substrate, which may help to speed up assembly. The heat dissipation members being integrally formed (e.g., from a single sheet of material) may also reduce the need to mechanically secure separate heat dissipation members together, which may speed up the manufacturing process and may also require fewer materials to be used. A second aspect comprises a haircare appliance comprising the heater assembly according to the first aspect. The heater arrangement may be used to heat a fluid flow (such as an airflow) through the haircare appliance. The heat dissipation member of the heat sink element may be located in a fluid flow path (such as an airflow path) through the haircare appliance, such that heat is transferred from the heat dissipation member into fluid flowing in the fluid flow path. A third aspect comprises a method of manufacturing a heater assembly, the method comprising: providing a heat sink element comprising at least one heat dissipation member, the at least one heat dissipation member comprising a base comprising a base portion having an underside, a heat dissipation fin extending upwardly from the base and a tab portion extending downwardly from the underside of the base portion; providing a heating element comprising a ceramic substrate; positioning the heat sink element such that the underside of the base portion and the tab portion face the ceramic substrate and the heat dissipation fin extends away from the ceramic substrate; applying a force to the heat sink element to urge the tab portion against the ceramic substrate; and while the force is applied, brazing the underside of the base portion and the tab portion to the ceramic substrate of the heating element. Brazing may provide a strong joint between the heat dissipation member and the ceramic substrate without needing to melt one or both of the heat dissipation member and the ceramic substrate. As such, this may reduce the likelihood of damaging one or both of the heat dissipation member and the ceramic substrate when attaching the heat dissipation member to the ceramic substrate. The braze filler may comprise a copper silver eutectic. The tab portion may be formed by stamping the base. Stamping the base may involve breaking the surface of the base, for example using a sharp tool, to push out the tab portion from the base. When the tab portion is formed in this way, no material needs to be added or removed from the base to form the tab portion. This may speed up manufacture of the heat dissipation member and may help to minimise waste. Brazing may comprise providing a braze filler material to a surface of the ceramic substrate, and the tab portion may wick the braze filler material between the ceramic substrate and the base. This may improve a connection between the ceramic substrate and the base by ensuring that the braze filler material fills a gap between the base and the ceramic substrate. Applying the force to the heat sink element may comprise applying the force to the heat sink element using a fixture. The fixture may be configured to engage with the heat dissipation member to provide an even force along the heat sink element. The fixture may apply a force to a plurality of heat dissipation members simultaneously. This may allow a plurality of heat dissipation members to be attached to the heating element at the same time. The method may comprise forming a plurality of tab portions in the base. The use of a plurality of tab portions may increase the strength of the joint between the heat dissipation member and the ceramic substrate compared to if only a single tab portion was used, as there are more points of connection between the heat dissipation member and the heating element. The plurality of tab portions may also provide improved thermal connection between the ceramic substrate and the base as more wicking paths are provided. The plurality of tab portions may also provide better compliance between the ceramic substrate and the heat dissipation member. The method may comprise forming the heat dissipation member by folding a sheet of metallic material. The method may comprise forming a plurality of heat dissipation members by folding the sheet of metallic material a plurality of times. The method may comprise forming the tab portion after folding the sheet of metallic material. The method may comprise forming the tab portion before folding the sheet of metallic material. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic cross-sectional view of a heater assembly; Figure 2 shows a schematic cross-sectional view of a heat sink element being brazed to a heating element; Figure 3 shows a schematic partial cross-sectional view of a further heater assembly; Figure 4 shows a schematic isometric view of the heat sink element of the heater assembly of Figure 3; Figure 5 shows a schematic partial cross-sectional view of the heat sink element of the heater assembly of Figure 3; Figure 6 shows a further schematic cross-sectional view of the heat sink element of the heater assembly of Figure 3; Figure 7 shows a schematic cross-sectional view of the heat sink element of Figures 4 to 6 being brazed to a heating element; Figure 8 shows a flowchart of a method of manufacturing a heater assembly; and Figure 9 shows a schematic view of a haircare appliance. DETAILED DESCRIPTION Figure 1 shows a cross-sectional view of a heater assembly 1. The heater assembly 1 comprises a heat sink element 2, a layer of braze filler material 3 and a heating element 4. The heating element 4 comprises a ceramic substrate 5 and at least one electrically conductive element (not shown), such as a track, wire, foil or film, disposed on or in the ceramic substrate 5. The heat sink element 2 is disposed on a surface 14 of the ceramic substrate 5 and is bonded to the surface of the ceramic substrate 5 by the braze filler material 3. In this example the braze filler material 3 comprises a silver copper eutectic, although in some examples, any type of suitable braze filler material could likewise be used. In this example, the heat sink element 2 comprises copper, although in some examples the heat sink element 2 may comprise any other metal or suitable material that readily dissipates heat. The heat sink element 2 comprises at least one heat dissipation member 6. The heat dissipation member 6 comprises a base 7, a heat dissipation fin 8 and a tab portion 9. The base 7 comprises a base portion 12 having an underside 13 that faces a surface 14 of the ceramic substrate 5. The base 7 is substantially planar and, when the heat sink element 2 is bonded to the surface 14 of the ceramic substrate 5 (as shown in Figure 1), the base 7 is substantially parallel to the ceramic substrate 5. In this example, the heat dissipation fin 8 is substantially orthogonal to the base 7, such that the heat dissipation fin 8 and the base 7 together form an “L-shaped” cross-sectional profile. In this example, the tab portion 9 is integrally formed with the base 7 and extends from the underside 13 of the base portion 12 in a direction towards the surface 14 of the ceramic substrate 5 (as shown in Figure 1). The tab portion 9 has a substantially trapezium shape with a length of approximately 1 mm and a height relative to the underside of the base portion 12 of approximately 0.6 mm and the tab portion 9 forms an oblique angle with the underside 13 of the base portion 12. The heat dissipation fin 8 extends in a direction away from the base portion 12 and away from the surface of the ceramic substrate 5. The braze filler material 3 is located between the underside 13 of the base portion 12 and the surface 14 of the ceramic substrate 5 and around the tab portion 9. In this example, the tab portion 9 is formed, prior to the heat sink element 2 being disposed on the surface 14 of the ceramic substrate 5, by stamping the base 7 with a tool that pierces the base 7 and pushes out part of the base 7 to form the tab portion 9. This creates a discontinuity 10 in the base 7 at the location where the tab portion 9 is formed. The discontinuity 10 comprises a hole that extends through the base 7 and the discontinuity 10 has a shape that corresponds to the tab portion 9. When the heat sink element 2 is bonded to the heating element 4, the tab portion 9 extends through the braze filler material 3 toward the heating element 4 and acts as a wick for the braze filler material 3, such that the braze filler material 3 is wicked from the surface of the ceramic substrate 5 towards the base 7 and into the discontinuity 10. In this example, the tab portion 9 is deformable relative to the ceramic substrate 5. Accordingly, the tab portion 9 may help to provide better contact between the heat dissipation member 6 and the surface of the ceramic substrate 5 because the tab portion 9 can deform during the brazing process to accommodate surface roughness of the ceramic substrate 5. Hence the required flatness tolerancing of the ceramic substrate 5 is less stringent than that currently required which may reduce the need for additional manufacturing steps to create a flat ceramic substrate 5. The tab portion 9 may also allow the base 7 of the heat dissipation member 6 to be positioned further away from the ceramic substrate 5. The braze filler material 3 fills a gap between the base 7 and the surface ceramic substrate 5 and may help to absorb strain between the ceramic substrate 5 and the base 7, caused by the ceramic substrate 5 and the base 7 having different coefficients of thermal expansion. As shown in Figure 2, when brazing the heat sink element 2 to the ceramic substrate 5, a fixture 11 is used to apply a force to the heat sink element 2 to urge the heat sink element 2 against the surface of the ceramic substrate 5. The fixture 11 comprises a finger 12 that extends towards the base 7 of the heat dissipation member 6 and applies a force in a direction shown by the arrow in Figure 2. While the force is being applied to the heat sink element 2 by the fixture 11, the braze filler material 3 is heated into a liquid form and is wicked by the tab portion 9 towards the base 7 of the heat dissipation member 6 of the heat sink 2. As the braze filler material 3 cools and solidifies, this creates a secure joint between the heat sink element 2 and the ceramic substrate 5. To improve the quality of the brazed connection between the heat sink element 2 and the ceramic substrate 5, the ceramic substrate 5 is coated in a layer of metallic material (not shown), in this case nickel, before the heat sink element 2 is brazed to the ceramic substrate 5. In this example, the layer of metallic material is formed by coating the ceramic substrate 5 in a metallisation paste and then sintering the ceramic substrate 5. In other examples, the layer of metallic material may be formed through electroplating or physical vapour deposition (PVD). The metallic layer forms a reaction layer between the ceramic substrate 5 and the braze filler material 3 to aid brazing of the heat sink element 2 to the ceramic substrate 5. Figure 3 shows a schematic partial cross-sectional view of a further heater assembly 20. The heater assembly 20 comprises a heating element 21, a layer of braze filler material 24 and a heat sink element 30. The heating element 21 comprises a ceramic substrate 22. The heatsink element 30 comprises plural heat dissipation members 32 (six in this example). The heat sink element 30 is disposed on a surface 31 of the ceramic substrate 22 and is bonded to the surface 31 of the ceramic substrate 22 by the braze filler material 24. The braze filler material 24 is the same braze filler material as described above in relation to Figures 1 and 2. The ceramic substrate 22 is the same as the ceramic substrate 5 described above in relation to Figures 1 and 2. The heat sink element 30 of the heater assembly 20 is shown in isolation in Figures 4 to 6. Figure 4 shows a schematic isometric view of the heat sink element 30, Figure 5 shows a schematic partial cross-sectional front view of the heat sink element 30 and Figure 6 shows a schematic cross-sectional side view of the heat sink element 30. The heat sink element 30 comprises a substantially rectangular cross-sectional shape when viewed in plan view and has a maximum height (H) of approximately 30mm, a length (L) of approximately 30mm and a width (W) of approximately 26mm. The heat sink element 30 comprises copper and comprises plural integrally formed heat dissipation members 32. Each heat dissipation member 32 comprises a base 34, two heat dissipation fins 36, 38 and eight tab portions 40 (the tab portions 40 best seen in Figure 6). In the interests of clarity, only two of the six heat dissipation members 32 are labelled in Figure 3. The height (H) of the heat dissipation fins 36, 38 changes across the width (W) of the heat sink element 30 such that the heat dissipation fins 36, 38 at opposite ends of the width (W) of the heat sink element 30 are shorter in height than the heat dissipation fins 36, 38 at a midpoint of the width (W) of the heat sink element 30. The heat dissipation fins 36, 38 are all substantially parallel to each other and are evenly spaced such that there is a gap of approximately 1.5mm between directly adjacent heat dissipation fins 36, 38. Directly adjacent heat dissipation members 32 are joined together at their uppermost ends (the ends of the heat dissipation members 32 furthest from their respective bases 34) by connecting portions 46 which extend between directly adjacent heat dissipation fins 36, 38 of directly adjacent heat dissipation members 32. The connecting portions 46 are substantially parallel to the bases 34 of the heat dissipation members 32. The base 34 of each heat dissipation member 32 is substantially planar and comprises a first edge 42 and a second edge 44. When the heat sink element 30 is attached to the ceramic substrate 22 (as shown in Figure 3), the base 34 is substantially parallel to the ceramic substrate 22. A first heat dissipation fin 36 extends from the first edge 42 of the base 34 and a second heat dissipation fin 38 extends from the second edge 44 of the base 34. The first heat dissipation fin 36 and the second heat dissipation fin 38 are both orthogonal to the base 34 and are parallel to each other, such that the two heat dissipation fins 36, 38 and the base 34 together form a “U-shaped” cross-sectional profile. As shown in Figure 6, the base 34 comprises eight discrete base portions 50 along the length (L) of the heat sink element 30. For the interests of clarity, only two of the eight base portions 50 are labelled in Figure 6. Each base portion 50 comprises an underside 51 that faces the surface 31 of the ceramic substrate 22 when the heat sink element 30 is bonded to the ceramic substrate 22. Each base portion 50 comprising one of the tab portions 40 and a gap between directly adjacent base portions 50 is approximately 1mm. When the base 34 is brazed to the heating element 22, only the base portions 50 are brazed, meaning that the base 34 is not brazed to the heating element 22 along its entire length. The tab portions 40 are integrally formed with the base 34 and extend from the underside 51 of the base portions 50 at a location between the first edge 42 and the second edge 44. The tab portions 40 extend from the underside 51 of the base portions 50 in a direction such that, when the heat sink element 30 is attached to the ceramic substrate 22 (as shown in Figure 3), the tab portions 40 extend towards the ceramic substrate 22. While only one tab portion 40 extends from each base portion 50 in Figure 6, in some examples more than one tab portion 40 may extend from each base portion 50. The tab portions 40 have the same shape and dimensions as the tab portion described above in relation to Figures 1 and 2. All the tab portions 40 extend from the base portions 50 in substantially the same direction. Although in the example shown in Figures 3 to 7 each heat dissipation member 32 comprises eight tab portions 40, in other examples each heat dissipation member 32 may comprise greater or fewer than eight tab portions 40. The tab portions 40 of this example are formed in the same way as the tab portions of the exampled described in relation to Figures 1 and 2. As with the example described above in relation to Figures 1 and 2, when brazing the heat sink element 30 to the ceramic substrate 22, a fixture 52 is used to apply a force to the heat sink element 30 to urge the heat sink element 30 against the ceramic substrate 22. As shown in Figure 7, the fixture 52 (only part of which is shown in Figure 6) comprises fingers 54 which extend between the heat dissipation fins 36, 38 of the heat dissipation members 32 of the heat sink element 30 towards the base 34. While only two fingers 54 are shown in Figure 6, the fixture 52 has a total number of fingers 54 equal to the total number of bases 34 present in the heat sink element 30. While the force is being applied to the heat sink element 30 by the fixture, the braze filler 24 is heated into a liquid form and is wicked by the tabs 40 towards the bases 34 of the heat dissipation members 32 of the heat sink element 30. As the braze filler 24 cools and solidifies, this creates a secure joint between the heat sink element 30 and the ceramic substrate 22. Figure 8 shows a flow chart of a method 100 of manufacturing the heater assembly 1, 20 discussed herein. The method 100 comprises providing 102 a heat sink element 2, 30 comprising a heat dissipation member 6, 32, the heat dissipation member 6, 32 comprising a base 7, 34 comprising a base portion having an underside, a heat dissipation fin 8, 36, 38 extending upwardly from the base 7, 34 and a tab portion 9, 40 extending downwardly from the underside of the base 7, 34. The heat sink element 2, 30 may be any heat sink element 2, 30 as described herein. The heat dissipation member 6, 32 of the heat sink element 2, 30 is formed by folding a sheet of copper into a desired shape for the heat sink element 2, 30. Once the sheet of copper has been folded into the desired shape, the providing 102 the heat dissipation member 6, 32 comprises forming the tab portions 9, 40 in the base 7, 34 by stamping the base 7, 34. This is done by using a tool to push the tab portions 9, 40 out of the base 7, 34. While the tab portions 9, 40 are formed after the copper sheet is folded in this example, in other examples the tab portions 9, 40 are formed in the copper sheet before it is folded. After providing 102 the heat sink element 2, 30, the method 100 comprises providing 104 a heating element 4, 21 comprising a ceramic substrate 5, 22. The heating element 4, 21 is the heating element 4, 21 as described herein. The heating element 4, 21 comprises a ceramic substrate 5, 22 that is coated in a metallisation paste and then sintered to form a metallic layer on the ceramic substrate 5, 22. The method 100 further comprises positioning 106 the heat sink element 2, 30 such that the base 7, 34 and the tab portion 9, 40 face the ceramic substrate 5, 22 and the heat dissipation fin 8, 36, 38 extends away from the ceramic substrate 5, 22. Once the heat sink element 2, 30 is in the correct position, the method 100 comprises applying 108 a force to the heat sink element 2, 30 to urge the tab portion 9, 40 against the ceramic substrate 5, 22. The force is applied to the heat dissipation member 6, 32 using the fixture 11, 52 to apply a force to the base 7, 34 of the heat dissipation member 6, 32 in a direction toward the heating element 4, 21. The fixture 11, 52 comprises fingers 12, 54 (one of which is shown in Figure 2 and two of which is shown in Figure 7) that extend between the heat dissipation fins 8, 36, 38 of the heat dissipation member 6, 32 to apply an even force across the heat sink element 2, 30. While the force is applied to the heat sink element 2, 30, the method 100 further comprises brazing 110 the underside 13, 51 of the base portion 12, 50 and the tab portions 9, 40 of the heat dissipation members 6, 32 of the heatsink element 2, 30 to the ceramic substrate 5, 22 of the heating element 4, 21. The brazing 110 comprises providing a braze filler material 3, 24 on the ceramic substrate 5, 22. The braze filler material 3, 24 is then heated to a liquid state whereby it is wicked by the tab portions 9, 40 between the ceramic substrate 5, 22 and the base 7, 34. As the braze filler material 3, 24 cools and solidifies, it forms a rigid joint between the heat sink element 2, 30 and the ceramic substrate 5, 22. Figure 9 shows a haircare appliance 200. The haircare appliance comprises a fluid inlet 210, a fluid outlet 220, a fan unit 230, a heater assembly 240 and a controller 250. The fan unit 230 is operable by the controller 250 to generate an airflow that is drawn in through the fluid inlet 210, passes over the heater assembly 240 and flows out of the fluid outlet 220. The heater assembly 240 is operable by the controller 250 to generate heat. As the airflow passes over the heater assembly 240, heat generated by the heater assembly 240 is dissipated into the airflow such that the airflow leaving the fluid outlet 220 has a higher temperature than the airflow entering the fluid inlet 210. The heater assembly 240 may be any of the heater assemblies 1, 20 described herein. In use, heat generated by the heating element 4, 22 is transferred to the heat sink element 2, 30 through thermal conduction. As the airflow generated by the fan unit 230 flows over the heat dissipation member 6, 32 of the heat sink element 2, 30, heat is transferred from the heat sink element 2, 30 into the airflow and is carried away from the heat sink element 2, 30. Although in the examples discussed above the heat sink element 2, 30 is made of copper, in other examples, the heat sink element 2, 30 may comprise another metallic material, such as aluminium or any alloy of copper and / or aluminium. Moreover, while in the examples discussed above the tab portions 9, 40 have a substantially trapezium shape, in other examples the tab portions 9, 40 may have any other suitable shape, such as a triangular shape or another quadrilateral. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

1. A heater assembly comprising:a heating element comprising a ceramic substrate; anda heat sink element disposed on a surface of the ceramic substrate, the heat sink element comprising:at least one heat dissipation member, wherein the at least one heat dissipation member comprises:a base comprising a base portion having an underside that faces the surface of the ceramic substrate;a tab portion extending from the underside of the base portion towards the surface of the ceramic substrate; anda heat dissipation fin extending from the base in a direction away from the surface of the ceramic substrate, the heat dissipation fin for dissipating heat produced by the heating element,wherein the heater assembly further comprises:a braze filler material bonding the heat sink element to the surface of the ceramic substrate, the braze filler material located between the underside of the base portion and the surface of the ceramic substrate and around the tab portion.

2. The heater assembly according to claim 1, wherein the tab portion is integrally formed with the base.

3. The heater assembly according to claim 1 or claim 2, wherein the tab portion is formed by a discontinuity in the base.

4. The heater assembly according to any one of claims 1 to 3, wherein the tab portion comprises a substantially triangular or trapezium shape.

5. The heater assembly according to any one of claims 1 to 4, wherein the tab portion has a length of no greater than 1.4 mm and / or a height relative to the underside of the base portion of no greater than 1.0 mm, and wherein optionally the tab portion has a length ofbetween 0.5 mm and 1.0 mm and / or a height relative to the underside of the base portion of between 0.4 mm and 0.8 mm.

6. The heater assembly according to any one of claims 1 to 5, wherein an angle formed between the tab portion and the underside of the base portion is oblique.

7. The heater assembly according to claim 6, wherein the base is substantially parallel to the ceramic substrate.

8. The heater assembly according to any one of claims I to 7, wherein the tab portion is deformable relative to the ceramic substrate.

9. The heater assembly according to any one of claims 1 to 8, wherein the base comprises a plurality of spaced apart base portions, each of the plurality of base portions having an underside that faces the surface of the ceramic substrate; and wherein the at least one heat dissipation member comprises a plurality of tab portions, a respective one of the plurality of tab portions extending from the underside of each of the base portions towards the surface of the ceramic substrate, wherein, the heat dissipation fin extends in a direction away from the plurality of base portions and the braze filler material is located between the underside of each of the plurality of base portions and the surface of the ceramic substrate and around each of the plurality of tab portions.

10. The heater assembly according to claim 9, wherein each tab portion of the plurality of tab portions extends from the underside of a respective base portion of the plurality of base portions in substantially the same direction.

11. The heater assembly according to any one of claims 1 to 10, wherein the heat dissipation member comprises a first heat dissipation fin and a second heat dissipation fin, the first heat dissipation fin is coupled to a first edge of the base, and the second heat dissipation fin is coupled to a second, opposite edge of the base.

12. The heater assembly according to any one of claims 1 to 11, wherein the heat sink element comprises a plurality of heat dissipation members.

13. The heater assembly according to claim 12, wherein the plurality of heat dissipation members are integrally formed.

14. A haircare appliance comprising the heater assembly according to any one of claims 1 to 13.

15. A method of manufacturing a heater assembly, the method comprising:providing a heat sink element comprising at least one heat dissipation member, the at least one heat dissipation member comprising a base comprising a base portion having an underside, a heat dissipation fin extending upwardly from the base and a tab portion extending downwardly from the underside of the base portion;providing a heating element comprising a ceramic substrate;positioning the heat sink element such that the underside of the base portion and the tab portion face the ceramic substrate and the heat dissipation fin extends away from the ceramic substrate;applying a force to the heat sink element to urge the tab portion against the ceramic substrate; andwhile the force is applied, brazing the underside of the base portion and the tab portion to the ceramic substrate of the heating element.

16. The method according to claim 15, wherein the tab portion is formed by stamping the base.

17. The method according to claim 15 or claim 16, wherein brazing comprises providing a braze filler to a surface of the ceramic substrate, and the tab portion wicks the braze filler between the ceramic substrate and the base.

Images